Channel state information (CSI) may be dropped in a variety of situations such as, for example, due to collision with higher-priority uplink control information. This may prevent an eNB from benefiting from CSI feedback from the UE in some serving cells. Therefore, it has been proposed that multi-cell periodic CSI be transmitted on a physical uplink shared channel (PUSCH). Multi-cell periodic CSI transmission refers to aggregated CSIs being transmitted in a subframe with a certain format. However, the transmission of multi-cell periodic CSI using PUSCH may be associated with the following issues.
Since at least one physical resource block (PRB) may be needed for the transmission, only one user equipment (UE) may be multiplexed. Further, a PUSCH-based solution may not enjoy the transmit diversity that can enhance the block error rate (BLER) performance significantly since there may not be any transmit diversity scheme for PUSCH.
Frequency hopping across slots within a subframe can provide frequency diversity gain. The hopping mode between inter-subframe hopping and intra- and inter-frequency hopping mode may be configured by cell-specific radio resource control (RRC) signaling. Given that the most UEs will not apply intra-subframe frequency hopping by using orthogonal code cover (OCC) on demodulation reference signal (DM RS) across the slots, a UE implementing the PUSCH-based solution may not be likely to use intra-frequency hopping.